How to tell Pavement mushroom from Yellow stainer

Cap 5-15 cm across, in young mushrooms compactly hemispherical to flat-convex, the edge often inrolled. Color white to cream, sometimes with a pale brownish tint in the center. Surface smooth, slightly sticky in wet weather. Often with a partial veil at the edge when young: a thin membranous fringe.

Cap 5-15 cm across; in young mushrooms firmly hemispherical to squared-off (a characteristic feature — the "square" young cap), later becoming convex to flat. Color white to cream, sometimes grayish-brown in the center. The most characteristic sign — touching the cap or its margin leaves bright chrome-yellow spots, especially noticeable in young mushrooms. The surface is smooth, slightly sticky in wet weather.

Gilled hymenophore: gills free, crowded. When young they are pale pink to bright pink, and with age they become dark brown to chocolate-blackish. Spore print dark brown.

Gilled hymenophore — gills free, crowded. When young — pale pinkish-gray, becoming with age dark brown, chocolate-blackish. Spore print dark brown. The gill color is typical of Agaricus — it doesn't help tell the yellow stainer apart.

Stem 3-8 cm tall, 1.5-3 cm thick, thick, meaty, cylindrical, narrowing toward the base. Color white. A distinctive double ring structure: in the upper part of the stem there are two membranous rings close together (hence the name bitorquis). This is the diagnostic feature of the species.

Stem 5-12 cm tall, 1-2 cm thick, cylindrical, with a pronounced bulbous base (a difference from other Agaricus species, whose stems are more even). Color white. The most important diagnostic sign: when cut, the flesh at the base of the stem and in the bulb is bright chrome yellow, often almost neon, and the reaction is fast (10-30 seconds). On the upper part — a white membranous ring, distinct in young mushrooms.

Flesh firm, meaty, white; when cut it slowly turns pinkish to brownish. Pleasant mushroomy smell with a fresh note. Mild taste, similar to the store-bought mushroom.

Flesh firm, white in the cap and upper stem, bright yellow at the base of the stem even when undamaged. When cut, THE BASE OF THE STEM TURNS BRIGHT CHROME YELLOW — the main diagnostic sign. The cap yellows too, but more weakly. The smell is distinct and unpleasant — ink, phenol, medicinal ointment, creosote.

Pleasant and mushroomy, like fresh store-bought button mushrooms. It does not smell of ink or medicine (that would point to the yellow stainer).

Distinct and unpleasant, with notes of ink, phenol, medicinal ointment, creosote, printer's ink. It comes out when you rub the flesh between your fingers, especially at the base of the stem. This smell is the most reliable sign: no edible Agaricus smells like this.